Are the boards powered 12v? Doubble check it pls
I have a corsair rm750 connected to the boards.
I am retrying everything again tonight i'll seewhat happens otherwise i'll set up TW.
Had some similiar behavior as I attached two HEX16A2 with Sata to Molex adapters to my current PSU.
As it turned out, the Sata To Molex Adapter was touching the board and could not be inserted completly.
A knife and some minor tweaks to the adapters and everything is working fine.
Maybe you could check, if this might be the case with your setup, too.
